2,008 research outputs found
Modeling the jet quenching, thermal resonance production and hydrodynamical flow in relativistic heavy ion collisions
The event topology in relativistic heavy ion collisions is determined by
various multi-particle production mechanisms. The simultaneous model treatment
of different collective nuclear effects at high energies (such as a hard
multi-parton fragmentation in hot QCD-matter, thermal resonance production,
hydrodynamical flows, etc.) is actual but rather complicated task. We discuss
the simulation of the above effects by means of Monte-Carlo model HYDJET++.Comment: Talk given at Workshop "Hot Quarks 2010" (La Londe Les Maures,
France, June 21-26, 2010); 4 pages including 2 figures as EPS-files; prepared
using LaTeX package for publication in Journal of Physics: Conference Serie
Dynamical vs geometric anisotropy in relativistic heavy-ion collisions: which one prevails?
We study the influence of geometric and dynamical anisotropies on the
development of flow harmonics and, simultaneously, on the second- and
third-order oscillations of femtoscopy radii. The analysis is done within the
Monte Carlo event generator HYDJET++, which was extended to dynamical
triangular deformations. It is shown that the merely geometric anisotropy
provides the results which anticorrelate with the experimental observations of
either (or ) or second-order (or third-order) oscillations of the
femtoscopy radii. Decays of resonances significantly increase the emitting
areas but do not change the phases of the radii oscillations. In contrast to
the spatial deformations, the dynamical anisotropy alone provides the correct
qualitative description of the flow and the femtoscopy observables
simultaneously. However, one needs both types of the anisotropy to match
quantitatively the experimental data.Comment: minor corrections, published versio
Will jets reduce the elliptic flow at LHC, while decays of resonances restore the constituent quark scaling?
Formation and evolution of the elliptic flow pattern in Pb+Pb collisions at
sqrt{s}=5.5 ATeV and in Au+Au collisions at sqrt{s}=200 AGeV are analyzed for
different hadron species within the framework of HYDJET++ Monte-Carlo model.
The model contains both hydrodynamic state and jets, thus allowing for a study
of the interplay between the soft and hard processes. It is found that jets are
terminating the rise of the elliptic flow with increasing transverse momentum.
Since jets are more influential at LHC compared to RHIC, the elliptic flow at
LHC should be weaker than that at RHIC. The influence of resonance decays on
particle elliptic flow is investigated also. These final state interactions
enhance the low-p_T part of the v_2 of pions and light baryons, and work
towards the fulfilment of idealized constituent quark scaling.Comment: 8 pages, 9 figures, 3 table
Anisotropic flow fluctuations in hydro-inspired freeze-out model for relativistic heavy ion collisions
The LHC data on event-by-event harmonic flow coefficients measured in PbPb
collisions at center-of-mass energy 2.76 TeV per nucleon pair are analyzed and
interpreted within the HYDJET++ model. To compare the model results with the
experimental data the unfolding procedure is employed. The essentially
dynamical origin of the flow fluctuations in hydro-inspired freeze-out approach
has been established. It is shown that the simple modification of the model via
introducing the distribution over spatial anisotropy parameters permits
HYDJET++ to reproduce both elliptic and triangular flow fluctuations and
related to it eccentricity fluctuations of the initial state at the LHC energy.Comment: 12 pages including 9 figures as EPS-files; prepared using LaTeX
package for publication in the European Physical Journal
Higher harmonics of azimuthal anisotropy in relativistic heavy ion collisions in HYDJET++ model
The LHC data on azimuthal anisotropy harmonics from PbPb collisions at
center-of-mass energy 2.76 TeV per nucleon pair are analyzed and interpreted in
the framework of the HYDJET++ model. The cross-talk of elliptic and
triangular flow in the model generates both even and odd harmonics of
higher order. Comparison with the experimental data shows that this mechanism
is able to reproduce the and centrality dependencies of
quadrangular flow , and also the basic trends for pentagonal and
hexagonal flows.Comment: 12 pages including 13 figures as EPS-files; prepared using LaTeX
package for publication in the European Physical Journal
Influence of jets and resonance decays on the constituent quark scaling of elliptic flow
The Monte Carlo HYDJET++ model, that contains both hydrodynamic state and
jets, is applied to study the influence of the interplay between soft and hard
processes on the formation of the elliptic flow in heavy-ion collisions at RHIC
and LHC energies. Jets are found to cease the hydro-like increase of the
elliptic flow with rising p_T. Since jets are more influential at LHC than at
RHIC, the v_2 at LHC should be weaker than that at RHIC. Violation of the
number-of-constituent-quark (NCQ) scaling is predicted. The decays of
resonances are found to enhance the low-p_T part of the elliptic flow of pions
and light baryons, and work toward the fulfillment of the NCQ scaling.Comment: 6 pages, talk given at the International Conference on Strangeness in
Quark Matter 2009 (SQM09
A Fast Hadron Freeze-out Generator
We have developed a fast Monte Carlo procedure of hadron generation allowing
one to study and analyze various observables for stable hadrons and hadron
resonances produced in ultra-relativistic heavy ion collisions. Particle
multiplicities are determined based on the concept of chemical freeze-out.
Particles can be generated on the chemical or thermal freeze-out hypersurface
represented by a parameterization or a numerical solution of relativistic
hydrodynamics with given initial conditions and equation of state. Besides
standard space-like sectors associated with the volume decay, the hypersurface
may also include non-space-like sectors related to the emission from the
surface of expanding system. For comparison with other models and experimental
data we demonstrate the results based on the standard parameterizations of the
hadron freeze-out hypersurface and flow velocity profile under the assumption
of a common chemical and thermal freeze-out. The C++ generator code is written
under the ROOT framework and is available for public use at
http://uhkm.jinr.ru/.Comment: 28 pages,7 figure
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